.heart {
  fill: red;
  padding-top:50px;
  width: 30px;
  animation-name: pulse;
  animation-duration: 2s;
  animation-iteration-count: infinite;
}

@keyframes pulse {
  0% { transform: scale(1); }
  50% { transform: scale(1.3); }
  100% { transform: scale(1); }
}

}